The present invention relates to a self-closing funnel of the kind which includes a downwardly narrowing flow receiving or catching part, a tubular flow directing spout which extends down from the flow receiving part, a float which is movably mounted in the spout, at least one throughflow chamber which is defined between the float and the spout, a float-controlled valve means, and a permanent magnet which influences the closing action of the valve means.
Self-closing funnels, i.e. funnels in which the flow of medium is cut off when a given level is reached in the container filled with the aid of the funnel, have earlier been proposed with the intention of simplifying container-filling procedures, e.g the filling of a gasoline or petrol tank from a gasoline or petrol can.
A funnel of the aforesaid kind is known from U.S. Pat. No. 4,712,595. This known funnel includes a float which is placed in the funnel spout and a float-controlled valve means mounted upstream of the spout. The valve means includes a permanent magnet which, when the valve has been closed as a result of the float moving into contact therewith, functions to hold the valve closed, therewith enabling any liquid remaining in the funnel to be poured back into a can or some corresponding receptacle.
Particular demands are placed on funnels of this kind when they are to be used to fill the fuel tanks of, for instance, small internal combustion engines used, for instance, to power lawn mowers, chain saws and similar tools in which the filling opening of the fuel tank may be very small and the tank may have the form of a flat container of small vertical extension or height, which means that it must be possible to fill the tank to an exact level precisely beneath the filling opening. If this were not possible, a relatively large part of the tank volume would remain unfilled or the tank would be overfilled.
In the case of small tank openings, it is essential that the float be prevented from engaging the rim of the filling hole as the spout is withdrawn from the tank and therewith unintentionally opening the valve. This requires that the float is arranged inside the spout which means that the float will have a very small cross-sectional area, since it must leave enough space between the outer surface of the float and the spout wall for liquid to flow through the spout. A float of small cross-sectional area will unavoidably exert a low dynamic upward force or lifting force. This may result in problems in achieving positive closing of the valve, unless floats of impractical lengths are used, and also in difficulties of always closing the valve at essentially the same liquid level in the tank.
The present invention is based on the realization that these problems can be solved when a greater part of the intrinsic weight of the float arrangement is balanced or compensated for with the aid of a spring, and when the float is arranged so that it will not be influenced by varying static pressures caused, among other things, by varying levels of liquid in the funnel.
U.S. Pat. No. 1,293,575 and DE-C 894,213 teach two closable funnels provided with spring means. These springs, however, are not used to balance out the intrinsic weight of the float but are used to ensure that the float will close the valve in the manner intended. In this case, the float action is utilized solely to release the force stored in the spring that is used to effect the valve closing movement. Furthermore, the floats taught by these prior publications are mounted below the spout, which is disadvantageous from several aspects.
Although the float of the earlier mentioned U.S. Pat. No. 4,712,595 is mounted in the spout, the float will close the valve means at different liquid levels in the container in dependence on the prevailing level of liquid in the funnel. This is because the bottom end of the spout is provided with a guide which has only a few small openings, whereas the valve opening surrounding the operating rod has a wide area. Thus, as will also be when the funnel is used, a column of liquid will be formed in the funnel, above the lower guide means. The float will therefore be subjected to varying hydrostatic pressures which correspond to the height of the liquid in the funnel. This means that the valve closing movement will be initiated at different levels in the container, since the requisite dynamic upward force will vary in dependence on the height of the liquid column.
This also applies to the funnels taught by U.S. Pat. No. 2,715,488, DE-C 348,251, FR-A1 2,606,855 and 2,610,305.
The publications SU-A11,375,560 and U.S. Pat. No. 493,994 teach other variants of self-closing funnels in which the respective floats are mounted in protective housings in the spout. This arrangement renders the funnels more complicated, more expensive and more space consuming. The weight of the float is not compensated for in the funnels structures taught by these earlier publications.